5.1 and 5.2 Flashcards
Define linear motion + give 2 track athletics examples
Motion in a straight or curved line, with all body parts moving the same distance, at the same speed in the same direction, e.g. 100m or 200 metres
The name of Newton’s 1st Law of Motion
The law of inertia
Define inertia
The resistance an object has to a change in its state of motion
Describe Newton’s 1st Law of motion
An (external) force is required to change the state of motion
What determines the inertia of an object
Its mass
The name of Newton’s 2nd law of motion
The law of acceleration
Describe Newton’s 2nd law of motion
The magnitude / size + direction of the force determines the magnitude and direction of the acceleration + the rate of acceleration is directly proportional to the size of the force causing the change
The equation used to calculate the size of a force
Force (N) = mass (KG) x acceleration (m/s^2), or F = ma
The name of Newton’s 3rd law of motion
The law of action / reaction
Describe Newton’s 3rd law of motion
For every action / force, there is an equal + opposite reaction / force
A ground reaction force (GRF)
The force exerted by the ground on the body in contact with it
Define a scalar quantity
When measurements are described in terms of just their size / magnitude (not direction)
2 examples of scalar quantities
Speed + distance
Define speed
The rate of change of position
The formula for calculating speed
Speed (m/s) = distance (m) / time (s)
Define distance
The length of a path that a body follows when moving from one position to another
What unit you should give the speed in if the question gives the distance in Km and the time in hours
Km/h
Where the line on your distance/time graph should finish for an out and back journey
At the bottom / x-axis
Define centre of mass
The point of balance/concentration of mass of a body
The effect that raising our arms has on the centre of mass of our body
It raises it
Where in the body the centre of mass of a person is normally when they’re standing
In the hip region
What characteristic of an individual determines their centre of mass
Gender
The difference between the location of the centre of mass in males and females + the reasons for this
It’s higher in males as they have more weight concentrated in their shoulders + upper body but women have more body weight concentrated around their hips
4 mechanical principles which affect stability
Height of the centre of mass, Position of the line of gravity, Area of the support base, Mass of the performer
The affect of lowering centre of mass on stability
It increases it
The position of the line of gravity which makes objects most stable
When it’s central over the base of support
The affect of increasing the area of the support base on the number of contact points + stability of an object
It increases the no. of contact points + increases stability
The effect of increasing the mass of a performer on their stability + the reason for this
It increases stability due to increased inertia
The 3 components which levers consist of
A fulcrum, resistance + effort
A fulcrum
The point/pivot about which the lever rotates
Define resistance (in terms of levers)
The weight to be moved (by the lever system)
Define effort (in terms of levers)
The force applied by the user/muscle of the lever system
What the skeleton forms (in terms of levers)
A system of levers
The parts of our bodies which act as levers
Bones
The parts of our bodies which act as fulcrums
Joints
what provides the effort in the lever systems of our body
Muscles
What forms the resistance in the lever systems of our bodies
The weight of the body part being moved (often against the force of gravity)
The 3 types of levers
1st, 2nd 3rd class levers
What the classification of levers depends on
The positions of the fulcrum, resistance + effort (in relation to each other)
The structure of a first class lever and the direction in which effort acts
The fulcrum is located between the effort and the resistance with effort acting downwards
How you draw a lever system
Like a see-saw with the fulcrum as a triangle ‘beneath the see-saw’
An example of a first class lever in the body
From: The movement of the head and neck during flexion and extension, Extension of the elbow
The direction in which effort acts for the 3 classifications of levers
Downwards for first class but upwards for 2nd and 3rd class levers
The structure of a second class lever
The resistance lies between the fulcrum and the effort
An example of a second class lever in the body
Plantarflexion of the ankle
The structure of a 3rd class lever
The effort is between the fulcrum and the resistance
An example of a 3rd class lever in the body
Hip/knee/elbow flexion
How to remember what lies in the middle of the 3 lever classifications
FRE (123) (F = the fulcrum in the middle of 1st class levers, R = resistance in the middle of 2nd class levers, E = effort in the middle of 3rd class levers)
What determines if a lever has mechanical advantage or mechanical disadvantage
The length of the force and resistance arms
The force arm
The (shortest perpendicular) distance between the fulcrum and effort
The resistance arm
The (shortest perpendicular) distance between the fulcrum and the resistance
Mechanical advantage
When the force arm is longer than the resistance arm
Mechanical disadvantage
When the resistance arm is longer than the force arm
How mechanical disadvantage affects the load a lever system can move
It decreases it
How mechanical disadvantage affects the speed at which a lever can move a load
It can do it faster
How mechanical disadvantage affects the range of movement
It increases it
How mechanical advantage affects the force required to move a load
It decreases it
